The Effects of Grape Polysaccharides Extracted from Grape By-Products on the Chemical Composition and Sensory Characteristics of White Wines

There is an increasing interest in the valorization of wine waste by-products. Grape pomace/marc can be an important source of polyphenols but also of polysaccharides (PSs). Therefore, the aim of this work was to extract PSs from grape pomace and musts and incorporate them into wines to improve their quality and valorize these residues. Two white wines were elaborated and treated with four different PS extracts obtained from white grape pomace, white must, a wine purified extract rich in RG-II, and commercial inactivated yeasts. In general, the use of grape PSs extracted from grape pomace or must improve some characteristics of wine, increasing the polysaccharide and volatile concentrations. These PS extracts can be useful to modulate some taste attributes such as an excess of acidity and bitterness and can also prevent the loss of volatile compounds associated with fruity and floral notes over time. This is the first study that shows the effects of grape polysaccharides on the chemical composition and sensory characteristics of white wines. Considering the obtained results, the grape pomace and surplus of musts can be considered valuable sources to obtain polysaccharide-rich products, opening a new opportunity to take advantage of by-products from the wine industry.     

Isolation,Characterization, and Compositional Analysis of Polysaccharides from Pinot Noir Wines: An Exploratory Study

It has been reported that polysaccharides in wine can interact with tannins and other wine components and modify the sensory properties of the wine. Unfortunately, the contribution of polysaccharides to wine quality is poorly understood, mainly due to their complicated structure and varied composition. In addition, the composition and molecular structure of polysaccharides in different wines can vary greatly. In this study, the polysaccharides were isolated from pinot noir wine, then separated into high-molecular-weight (PNWP-H) and low-molecular-weight (PNWP-L) fractions using membrane-based ultrafiltration. Each polysaccharide fraction was further studied using size exclusion chromatography, UV–Vis, FT-IR, matrix-assisted laser desorption/ionization–high-resolution mass spectrometry, and gas chromatography-mass spectrometry (GC-MS). The results showed that PNWP-L and PNWP-H had different chemical properties and compositions. The FT-IR analysis showed that PNWPs were acidic polysaccharides with α- and β-type glycosidic linkages. PNWP-L and PNWP-H had different α- and β-type glycosidic linkage structures. FT-IR showed stronger antisymmetric and symmetric stretching vibrations of carboxylate anions of uronic acids in PNWP-L, suggesting more uronic acid in PNWP-L. The size exclusion chromatography results showed that over 72% of the PNWP-H fraction had molecular sizes from 25 kDa to 670 kDa. Only a small percentage of smaller molecular polysaccharides was found in the PNWP-H fraction. In comparison, all of the polysaccharides in the PNWP-L fraction were below 25 KDa, with a majority distributed approximately 6 kDa (95.1%). GC-MS sugar composition analysis showed that PNWP-L was mainly composed of galacturonic acid, rhamnose, galactose, and arabinose, while PNWP-H was mainly composed of mannose, arabinose, and galactose. The molecular size distribution and sugar composition analysis suggested that the PNWP-L primarily consisted of rhamnogalacturonans and polysaccharides rich in arabinose and galactose (PRAG). In comparison, PNWP-H were mostly mannoproteins and polysaccharides rich in arabinose and galactose (PRAG). Further research is needed to understand the impacts of these fractions on wine organoleptic properties.     

Effect of Sonication Treatment and Maceration Time in the Extraction of Polysaccharide Compounds during Red Wine Vinification

The application of high-power ultrasounds (US) at 28 kHz to the crushed grapes and the use of different pomace contact times caused changes in the content and composition of monosaccharides and polysaccharides in the musts and wines. These differences were maintained from the moment of pressing (end of maceration) until the end of the alcoholic fermentation. The US increased the content of monosaccharides and polysaccharides in the musts by facilitating their extraction from the solid parts during maceration. The application of medium maceration time (3 days) to sonicated grapes led to an extraction of polysaccharides rich in arabinose and galactose, rhamnogalacturonan type II (RG-II) and mannoproteins (MP), similar to that observed in the control wines made with an extended maceration of 7 days (968.21 vs. 1029.45; 895.04 vs. 1700.50; 356.81 vs. 343.95, respectively). This fact was attributed to a higher extraction in the must during the sonication process and to an important release of pectic polysaccharides during the pressing of the sonicated pomace, which is reported here for the first time. Therefore, the US technology could be useful for increasing the polysaccharide content in the wines or for reducing the maceration time needed to achieve certain levels of wine polysaccharides.     

Determination of glutathione content in grape juice and wine by high-performance liquid chromatography with fluorescence detection

A modified preparation of sample was developed for the determination of glutathione content in grape juice and wine by high-performance liquid chromatography with fluorescence detection, using on-line pre-column derivatization. Ice-cold deoxygenated methanol was used to deactivate the oxidation enzymes in juices or wines and keep the glutathione stable. The optimum recovery of glutathione content in grape juice and wine was obtained when either the sample of grape juice or wine was mixed in ice-cold deoxygenated methanol in the ratio 10:90 (v:v) and further diluted in sodium acetate buffer in the ratio 1:1 (v:v). The optimized method was validated for linearity, limit of detection, limit of quantification, precision and uncertainty. According to the validation data the method is appropriate for the determination of glutathione content in grape juice and wine. Glutathione contents in grape juices made from White Muscat grapes and Sauvignon Blanc wines were analysed. The average glutathione content in 28 young Sauvignon Blanc wines was 12.5 mg L⁻¹.     

Commercial Mannoproteins Improve the Mouthfeel and Colour of Wines Obtained by Excessive Tannin Extraction

In the production of red wines, the pressing of marcs and extended maceration techniques can increase the extraction of phenolic compounds, often imparting high bitterness and astringency to finished wines. Among various oenological products, mannoproteins have been shown to improve the mouthfeel of red wines. In this work, extended maceration (E), marc-pressed (P), and free-run (F) Sangiovese wines were aged for six months in contact with three different commercial mannoprotein-rich yeast extracts (MP, MS, and MF) at a concentration of 20 g/hL. Phenolic compounds were measured in treated and control wines, and sensory characteristics related to the astringency, aroma, and colour of the wines were studied. A multivariate analysis revealed that mannoproteins had a different effect depending on the anthocyanin/tannin (A/T) ratio of the wine. When tannins are strongly present (extended maceration wines with A/T = 0.2), the MP conferred mouthcoating and soft and velvety sensations, as well as colour stability to the wine. At A/T = 0.3, as in marc-pressed wines, both MF and MP improved the mouthfeel and colour of Sangiovese. However, in free-run wine, where the A/T ratio is 0.5, the formation of polymeric pigments was allowed by all treatments and correlated with silk, velvet, and mouthcoat subqualities. A decrease in bitterness was also obtained. Commercial mannoproteins may represent a way to improve the mouthfeel and colour of very tannic wines.     

Phenolic concentrations and antioxidant properties of wines made from north american grapes grown in china

The characteristics of wine phenolics found in several North American and (for comparison) European grape cultivars grown in China were analyzed. This was done to find non-Vitis vinifera wines with prominent features in order to diversify the kinds of wines. The phenolic richness and antioxidant activity decreased in the order: red > rose > white wines. In the red wines, the American grape 'Cynthiana' had the highest total concentrations of phenols, anthocyanins, flavonols and phenolic acids, as well as antioxidant capacity, followed by the French hybrid 'Chambourcin', the lowest were detected in two European grape varieties, 'Merlot' and 'Cabernet Sauvignon', while the total flavon-3-ols levels were reversed among these red grape cultivars. The highest concentration of stilbenes out of all the wines analyzed was found in the 'Merlot' variety. There were significant differences among wine phenolic compositions between North American and European grape cultivars. The antioxidant activities were significantly related to the concentrations of total phenols (r2 = 0.996), anthocyanins (r2 = 0.984), flavonols (r2 = 0.850) and gallic acid (r2 = 0.797). The prominent features of wine aroma and nutrition could make the American grape wines attractive to consumers. It is therefore necessary to perform further research on cultural practices and wine making involving these grapes.     

Identification and semi-quantitative determination of gum Arabic in wines by GC-MS and size exclusion chromatography

A method for the identification and the semi-quantitative determination of the food additive gum Arabic in wines is described. Tests carried out on solutions spiked with known amounts of wine and gum Arabic polysaccharides allowed to define the suitable conditions for their quantitative precipitation and size exclusion analysis. CG-MS analyses of the different recovered fractions allowed to discriminate between gum Arabic and wine polysaccharides through the identification of glucose and mannose present only in wine polysaccharides. The proposed method was based on the wine polysaccharides free peak area obtained by size exclusion chromatography. The same cut-off time was always used both in the preparation of the calibration plot and in the analysis of the real samples. Gum Arabic was determined in a ratio of 1/10 w/w with wine polysaccharides with a detection limit of 0.074 mg ml(-1) which is lower than the lowest gum Arabic amount usually added into wines. Owing to the moderately low natural variability of the gum Arabic standards the described procedure is suitable for a semi-quantitative analysis even if its accuracy allowed a quite reliable determination of the gum Arabic amount usually added to wine.     

Feature extraction and selection from volatile compounds for analytical classification of Chinese red wines from different varieties

This work was undertaken to evaluate whether it is possible to determine the variety of a Chinese wine on the basis of its volatile compounds, and to investigate if discrimination models could be developed with the experimental wines that could be used for the commercial ones. A headspace solid-phase microextraction gas chromatographic (HS-SPME-GC) procedure was used to determine the volatile compounds and a blind analysis based on Ac/Ais (peak area of volatile compound/peak area of internal standard) was carried out for statistical purposes. One way analysis of variance (ANOVA), principal component analysis (PCA) and stepwise linear discriminant analysis (SLDA) were used to process data and to develop discriminant models. Only 11 peaks enabled to differentiate and classify the experimental wines. SLDA allowed 100% recognition ability for three grape varieties, 100% prediction ability for Cabernet Sauvignon and Cabernet Gernischt wines, but only 92.31% for Merlot wines. A more valid and robust way was to use the PCA scores to do the discriminant analysis. When we performed SLDA this way, 100% recognition ability and 100% prediction ability were obtained. At last, 11 peaks which selected by SLDA from raw analysis set had been identified. When we demonstrated the models using commercial wines, the models showed 100% recognition ability for the wines collected directly from winery and without ageing, but only 65% for the others. Therefore, the varietal factor was currently discredited as a differentiating parameter for commercial wines in China. Nevertheless, this method could be applied as a screening tool and as a complement to other methods for grape base liquors which do not need ageing and blending procedures.     

Optimized determination of calcium in grape juice,wines, and other alcoholic beverages by atomic absorption spectrometry

This paper describes a study of the different methods of sample preparation for the determination of calcium in grape juice, wines, and other alcoholic beverages by flame atomic absorption spectrometry; results are also reported for the practical application of these methods to the analysis of commercial samples produced in Spain. The methods tested included dealcoholization, dry mineralization, and wet mineralization with heating by using different acids and/or mixtures of acids. The sensitivity, detection limit, accuracy, precision, and selectiviy of each method were established. Such research is necessary because of the better analytical indexes obtained after acid digestion of the sample, as recommended by the European Union, which advocates the direct method. In addition, although high-temperature mineralization with an HNO3-HCIO4 mixture gave the best analytical results, mineralization with nitric acid at 80 degrees C for 15 min gave the most satisfactory results in all cases, including those for wines with high levels of sugar and beverages with high alcoholic content. The results for table wines subjected to the latter treatment had an accuracy of 98.70-99.90%, a relative standard deviation of 2.46%, a detection limit of 19.0 microg/L, and a determination limit of 31.7 microg/L. The method was found to be sufficiently sensitive and selective. It was applied to the determination of Ca in grape juice, different types of wines, and beverages with high alcoholic content, all of which are produced and widely consumed in Spain. The values obtained for Ca were 90.00 +/- 20.40 mg/L in the grape juices, 82.30 +/- 23.80 mg/L in the white wines, 85.00 +/- 30.25 mg/L in the sweet wines, 84.92 +/- 23.11 mg/L in the red wines, 85.75 +/- 27.65 mg/L in the rosé wines, 9.51 +/- 6.65 mg/L in the brandies, 11.53 +/- 6.55 mg/L in the gin, 7.3 +/- 6.32 mg/L in the pacharán, and 8.41 +/- 4.85 mg/L in the anisettes. The method is therefore useful for routine analysis in the quality control of these beverages.     

Extraction of flavan-3-ols from grape seed and skin into wine using simulated maceration

Simulated maceration assays were carried out in wine model systems using increasing ethanol percentages from 0 to 12.5%, in order to study the extraction of flavan-3-ol monomers and oligomers from grape skins and seeds. The amount of flavan-3-ols transferred to the solutions improves with the increase in the alcohol percentage, although flavanols were much more readily released from grape skins than from seeds. Maximum release of flavanols from the skins is reached after 24 h of maceration in 12.5% ethanol, whereas long maceration and higher ethanol percentages were required for extraction from the seeds, from which maximum flavanol extraction was observed after 2-3 weeks of maceration. Thus, the length of the maceration not only had an influence in the total levels of flavanols reached in the wines, but also in their qualitative composition. The contribution of the seeds to the flavanol composition of the model wines was found to range from about 40% at 24 h of maceration in 12.5% ethanol to as high as 90% after 3 weeks. Gallocatechin was the major flavanol contributed by the skins and catechin by the seeds of the grape variety used (Vitis vinifera cv. Viura). Flavanol extraction was also followed during winemaking of commercial red wines, reaching similar conclusions to that obtained from the model assays.     

HPLC-DAD-MS Determination of Colored and Colorless Phenolic Compounds in Kalecik Karasi Wines: Effect of Different Vineyard Locations

Phenolic composition of wines from Kalecik karasi, a native grape variety grown in Turkey, and influence of different vineyard locations on these compounds were investigated. High performance liquid chromatography-diode array detector (HPLC-DAD) and mass spectrometry (MS) were used for the phenolic compound analysis. Fourteen anthocyanins, six flavanols, twelve phenolic acids, and six flavonols were identified and quantified. It was observed that total phenolic content in wine from Ankara region was clearly higher than in wine from Nevsehir. Sensory analysis was also used to investigate the influences of the vineyard location. Based upon sensory analysis, the wines obtained from Ankara region had higher color, harmony, astringency aftertaste, astringency, flavor, and body character than wine from Nevsehir.     

Quantification of chitinase and thaumatin-like proteins in grape juices and wines

Chitinases and thaumatin-like proteins are important grape proteins as they have a great influence on wine quality. The quantification of these proteins in grape juices and wines, along with their purification, is therefore crucial to study their intrinsic characteristics and the exact role they play in wines. The main isoforms of these two proteins from Chardonnay grape juice were thus purified by liquid chromatography. Two fast protein liquid chromatography (FLPC) steps allowed the fractionation and purification of the juice proteins, using cation exchange and hydrophobic interaction media. A further high-performance liquid chromatography (HPLC) step was used to achieve higher purity levels. Fraction assessment was achieved by mass spectrometry. Fraction purity was determined by HPLC to detect the presence of protein contaminants, and by nuclear magnetic resonance (NMR) spectroscopy to detect the presence of organic contaminants. Once pure fractions of lyophilized chitinase and thaumatin-like protein were obtained, ultra-HPLC (UHPLC) and enzyme-linked immunosorbent assay (ELISA) calibration curves were constructed. The quantification of these proteins in different grape juice and wine samples was thus achieved for the first time with both techniques through comparison with the purified protein calibration curve. UHPLC and ELISA showed very consistent results (less than 16% deviation for both proteins) and either could be considered to provide an accurate and reliable quantification of proteins in the oenology field.     

Evidence of vintage effects on grape wines using H NMR-based metabolomic study

The chemical composition of grape wines varies with grape variety, environmental factors of climate and soil, and bacterial strains, which can each affect the wine quality. Using ¹H NMR analysis coupled with multivariate statistical data sets, we investigated the effects of grape vintage on metabolic profiles of wine and the relationship between wine metabolites and meteorological data. Principal component analysis (PCA) showed a clear differentiation between Meoru wines that were vinified with the same yeast strain and Meoru grapes harvested from the same vineyard but with a different vintage. The metabolites contributing to the differentiation were identified as 2,3-butandiol, lactic acid, alanine, proline, γ-aminobutyric acid (GABA), choline, and polyphenols, by complementary PCA loading plot. Markedly higher levels of proline, lactic acid and polyphenols were observed in the 2006 vintage wines compared to those of 2007 vintage, showing excellent agreement with the meteorological data that the sun-exposed time and rainfall in 2006 were approximately two times more and four times less, respectively, than those in 2007. These results revealed the important role of climate during ripening period in the chemical compositions of the grape. This study highlights the reliability of NMR-based metabolomic data by integration with meteorological data in characterizing wine or grape.     

Application of Amperometric Enzyme Biosensors for Wine and Must Analysis

The work presents application of amperometric biosensors based on platinum printed electrodes and immobilized enzymes alcohol oxidase, glucose oxidase and lactate oxidase for wine analysis. Created devices demonstrate wide dynamic range of work, good stability and high selectivity to the substrate, and are successfully applied for analysis of such complex mixtures as wine and must. Good correlation of the results of analysis of different wines and must obtained by amperometric biosensors and chromatography method is shown. Created biosensors can be used as a basis of commercial device for express analysis of ethanol, glucose and lactate in wine and must during its fermentation.     

Study of biologically active amines in grapes and wines by HPLC

Summary The biologically active amines agmatine, cadaverine, histamine, phenethylamine, putrescine, spermidine, and tyramine have been determined in different varieties of grape, aszu grape, wine and aszu wine from the Tokaj region of Hungary. Ion pairs formed between the amines and octanesulphonic acid were separated by liquid chromatography on a μBondapak C₁₈ reversed-phase column, and spectrofluorimetric detection was performed after post-column derivatization witho-phthalaldehyde and 2-mercaptoethanol. The method was linear for the amines between 0.1 and 10 mg L⁻¹, and for spermidine between 1 and 30 mg L⁻¹. Comparison of the results revealed that the qualitative and quantitative content of biologically active amines was mostly determined by the vintage of the wine and the technology used for wine-making. The biogenic amine content of Tokaj wines is well below suggested limits for any of the amines, showing that the wine-making technology of the Tokaj region is of high quality. The levels of biologically active amines (identified and quantified by HPLC) in grapes, wines and aszu wines can provide useful information about the weather, growth ofBotrytis cinerea in Tokaj, and aspects of the methods used for wine-making. Presented at Balaton Symposium on High Performance Separation Methods, Siófok, Hungary, September 1–3, 1999     

DCMC as a Promising Alternative to Bentonite in White Wine Stabilization. Impact on Protein Stability and Wine Aromatic Fraction

Protein haze in white wine is one of the most common non-microbial defects of commercial wines, with bentonite being the main solution utilized by the winemaking industry to tackle this problem. Bentonite presents some serious disadvantages, and several alternatives have been proposed. Here, an alternative based on a new cellulose derivative (dicarboxymethyl cellulose, DCMC) is proposed. To determine the efficiency of DCMC as a bentonite alternative, three monovarietal wines were characterized, and their protein instability and content determined by a heat stability test (HST) and the Bradford method, respectively. The wines were treated with DCMC to achieve stable wines, as shown by the HST, and the efficacy of the treatments was assessed by determining, before and after treatment, the wine content in protein, phenolic compounds, sodium, calcium, and volatile organic compounds (VOCs) as well as the wine pH. DCMC applied at dosages such as those commonly employed for bentonite was able to reduce the protein content in all tested wines and to stabilize all but the Moscatel de Setúbal varietal wine. In general, DCMC was shown to induce lower changes in the wine pH and phenolic content than bentonite, reducing the wine calcium content. Regarding which VOCs are concerned, DCMC produced a general impact similar to that of bentonite, with differences depending on wine variety. The results obtained suggest that DCMC can be a sustainable alternative to bentonite in protein white wine stabilization.     

Two Sides to One Story—Aroma Chemical and Sensory Signature of Lugana and Verdicchio Wines

Lugana and Verdicchio are two Italian white wines with a Protected Designation of Origin (PDO) label. These two wine types are produced in different regions using the same grape variety. The aim of this work is to investigate the existence of volatile chemical markers that could help to elucidate differences between Lugana and Verdicchio wines both at chemical and sensory levels. Thirteen commercial wine samples were analyzed by Gas Chromatography-Mass Spectrometry (GC-MS), and 76 volatile compounds were identified and quantified. Verdicchio and Lugana had been differentiated on the basis of 19 free and glycosidically bound compounds belonging to the chemical classes of terpenes, benzenoids, higher alcohols, C₆ alcohols and norisoprenoids. Samples were assessed by means of a sorting task sensory analysis, resulting in two clusters formed. These results suggested the existence of 2 product types with specific sensory spaces that can be related, to a good extend, to Verdicchio and Lugana wines. Cluster 1 was composed of six wines, 4 of which were Lugana, while Cluster 2 was formed of 7 wines, 5 of which were Verdicchio. The first cluster was described as “fruity”, and “fresh/minty”, while the second as “fermentative” and “spicy”. An attempt was made to relate analytical and sensory data, the results showed that damascenone and the sum of 3 of esters the ethyl hexanoate, ethyl octanoate and isoamyl acetate, was characterizing Cluster 1. These results highlighted the primary importance of geographical origin to the volatile composition and perceived aroma of Lugana and Verdicchio wines.     

Screening of Yeast in Various Vineyard Soil and Study on Its Flavor Compounds from Brewing Grape Wine

In order to screen out Saccharomyces cerevisiae suitable for table grape fermentation, and compare it with commercial Saccharomyces cerevisiae in terms of fermentation performance and aroma producing substances, differences of fermentation flavor caused by different strains were discussed. In this experiment, yeast was isolated and purified from vineyard soil, 26s rDNA identification and fermentation substrate tolerance analysis were carried out, and the causes of flavor differences of wine were analyzed from three aspects: GC-MS, PCA and sensory evaluation. The results showed that strain S1 had the highest floral aroma fraction, corresponding to its high production of ethyl octanoate and other substances, and it had the characteristics of high sugar tolerance. The fruit sensory score of S3 wine was the highest among the six wines. Through exploration and analysis, it was found that compared with commercial Saccharomyces cerevisiae, the screened strains had more advantages in fermenting table grapes. The flavor of each wine was directly related to the growth characteristics and tolerance of its strains.     

Evaluation of Anthocyanin Profile and Color in Sweet Cherry Wine: Effect of Sinapic Acid and Grape Tannins during Aging

Cherries are rich in bioactive phenolic compounds and are often fermented into cherry wines. The degradation of anthocyanins during storage will cause color deterioration. The study aimed to utilize sinapic acid and grape tannins in cherry wine to maintain a high fraction in the colored forms of anthocyanins, in order to maximize the color intensity, the latter being associated with good product quality. The effects on the anthocyanin profile and on color parameters of copigments, utilizing spectral measurement combined with UPLC-MS quantitative analysis, have been evaluated in sweet cherry wines. The copigmentation effect of sinapic acid and grape tannin was accompanied by the bathochromic shift and the hyperchromic effect, which lead to an increase in color intensity (lower L*, higher a* and b*). During the aging process, sinapic and grape tannin increased the content of pyranoanthocyanins in cherry wine, especially the addition of sinapic acid makes the cherry wine generate 10-syringyl-pyranocyanidin-3-rutinoside. These results demonstrate that sinapic acid is suitable for adding before alcohol fermentation, while grape tannins can be added before aging.     

Pattern Recognition of Nebbiolo Wine as a Function of the Fungicide Treatment of the Grape

ABSTRACT

Principal component analysis and classification techniques were used to investigate the effect on the properties of wine of different fungicide treatments performed on the grapes. 55 variables were determined, 17 on the grape just-collected and the others on the wines. 27 samples of grape and wine were considered, produced in 1992, 1993" acceptdate="and 1994. The wines were classified as a function of the production year but no important correlation was found between fungicide treatment and the wine features. The classification was performed by a SIMCA method.

Clustering analysis, on the other hand, allowed a separation of the wine samples in three clusters, relative to three main kinds of grape treatments, i.e. based on i) copper sulfate, ii) copper hydroxide and iii) Mancozeb (the only one that does not contain Cu). The treatments based on copper oxychloride and the blank, that are the less active or characterized treatments, gave mixed results within the three clusters.